This invention relates to the structure of electric solenoids and more particularly to electric solenoids of the general type disclosed in U.S. patent application Ser. No. 450,310 filed Mar. 12, 1974, now U.S. Pat. No. 3,900,822, and assigned to the same assignee as this invention. More particularly, the present invention may be considered as an improvement to the structure as shown and described in the above-identified copending U.S. application.
In the copending application, a proportional solenoid is described in which the armature is subject to conditions of possible side-loading in the event of a lack of concentricity between the relatively moving parts, that is between the fixed base and hub on the one hand and the armature on the other hand, and an arrangement is disclosed and claimed by which the armature is supported to assure concentricity of the armature with respect to the base.
Such solenoids are built-up structures in which a hub member is retained in respective alignment primarily by reason of the force exerted by tie bolts extending between the opposite end plates. It is important that the hub be maintained in a coaxial alignment relation to the bases and the armature in the event of shock, vibration, or other external forces.